Interpretive Summary: A new technique for creating computer representations of the earth's surface has recently been developed. Called synthetic aperture radar, this approach uses images captured from satellites or aircraft to produce a three-dimensional model of elevation. This approach is very promising because it can potentially produce higher quality data than current techniques. Models of the earth's surface are important for hydrologic research, and it is desirable to have as accurate and finely detailed map as possible. This study investigated the accuracy of a new surface model and compared it to several other data sets that cover the same area. It was found that the new method creates a rougher, more detailed surface than the other techniques.

Technical Abstract:
A high resolution digital elevation model (DEM) was constructed for the USDA-ARS Walnut Gulch Experimental Watershed located in southeast Arizona using interferometric synthetic aperture radar (IFSAR) processing techniques. Three lower resolution DEMs had previously been constructed for the watershed; a 40m photogrametrically derived surface, a combination USGS SLevel I and II 30m surface, and a derivative 10m surface. The IFSAR DEM, with a resolution of 2.5m and high vertical accuracy, is potentially a significant improvement in terrain representation. This study investigates the differences in topographic representation among the photo, USGS, and IFSAR DEMs and illustrates the influence they have on hydrologic and geomorphic studies. Watershed characteristics such as area, geometry, drainage network, slope, and drainage density, derived from the DEMs, are compared. Results from these studies demonstrate the impact of using IFSAR technology on watershed hydrologic and geomorphic research at a range of watershed scales.